Cell necrosis apparatus and method

ABSTRACT

A cell necrosis apparatus includes an introducer with a distal end sufficiently sharp to penetrate tissue, an energy delivery including a plurality of electrodes and a slidable sensing member. Each electrode of the plurality of electrodes has a tissue piercing distal end and is positionable in the introducer as the introducer is advanced through tissue. At least one electrode of the plurality of electrodes is deployable with curvature from the introducer. The slidable sensing member is positionable within the introducer and electrically coupled to the energy delivery device. The sensing member is configured to measure a property of the energy delivery device or at least one electrode of the plurality of electrodes.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 09/148,571, filedSep. 4, 1998, now U.S. Pat. No. 6,235,023, which is acontinuation-in-part application of U.S. Ser. No. 09/047,845, filed Mar.25, 1998, now U.S. Pat. No. 5,980,517, which is a continuation-in-partof U.S. Ser. No. 09/020,182, now U.S. Pat. No. 6,132,425, filed Feb. 6,1998, which is a continuation-in-part of U.S. Ser. No. 08/963,239, filedNov. 3, 1997, now pending, which is a continuation-in-part of U.S. Ser.No. 08/515,379, filed Aug. 15, 1995, now U.S. Pat. No. 5,683,384, all ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to a cell necrosis apparatus, and moreparticularly to a cell necrosis apparatus with an introducer anddeployable electrodes.

2. Description of the Related Art

Current open procedures for treatment of tumors are extremely disruptiveand cause a great deal of damage to healthy tissue. During the surgicalprocedure, the physician must exercise care in not cutting the tumor ina manner that creates seeding of the tumor, resulting in metastasis. Inrecent years, development of products has been directed with an emphasison minimizing the traumatic nature of traditional surgical procedures.

There has been a relatively significant amount of activity in the areaof hyperthermia as a tool for treatment of tumors. It is known thatelevating the temperature of tumors is helpful in the treatment andmanagement of cancerous tissues. The mechanisms of selective cancer celleradication by hyperthermia are not completely understood. However, fourcellular effects of hyperthermia on cancerous tissue have been proposed,(i) changes in cell or nuclear membrane permeability or fluidity, (ii)cytoplasmic lysomal disintegration, causing release of digestiveenzymes, (iii) protein thermal damage affecting cell respiration and thesynthesis of DNA or RNA and (iv) potential excitation of immunologicsystems. Treatment methods for applying heat to tumors include the useof direct contact radio-frequency (RF) applicators, microwave radiation,inductively coupled RF fields, ultrasound, and a variety of simplethermal conduction techniques.

Among the problems associated with all of these procedures is therequirement that highly localized heat be produced at depths of severalcentimeters beneath the surface of the skin.

Attempts to use interstitial local hyperthermia have not proven to bevery successful. Results have often produced nonuniform temperaturesthroughout the tumor. It is believed that tumor mass reduction byhyperthermia is related to thermal dose. Thermal dose is the minimumeffective temperature applied throughout the tumor mass for a definedperiod of time. Because blood flow is the major mechanism of heat lossfor tumors being heated, and blood flow varies throughout the tumor,more even heating of tumor tissue is needed to ensure effectivetreatment.

The same is true for ablation of the tumor itself through the use of RFenergy. Different methods have been utilized for the RF ablation ofmasses such as tumors. Instead of heating the tumor it is ablatedthrough the application of energy. This process has been difficult toachieve due to a variety of factors including, (i) positioning of the RFablation electrodes to effectively ablate all of the mass, (ii)introduction of the RF ablation electrodes to the tumor site and (iii)controlled delivery and monitoring of RF energy to achieve successfulablation without damage to non-tumor tissue.

Thus, non-invasive procedures for providing heat to internal tissue havehad difficulties in achieving substantial specific and selectivetreatment.

Examples illustrating the use of electromagnetic energy to ablate tissueare disclosed in: U.S. Pat. No. 4,562,200; U.S. Pat. No. 4,411,266; U.S.Pat. No. 4,838,265; U.S. Pat. No. 5,403,311; U.S. Pat. No. 4,011,872;U.S. Pat. No. 5,385,544; and U.S. Pat. No. 5,385,544.

There is a need for a cell necrosis apparatus with at least twoelectrodes that are deployable with curvature from an introducer. Thereis another need for a cell necrosis apparatus with at least twoelectrodes that are selectably deployable with curvature from anintroducer to a desired deployed geometric configuration. There is yet afurther need for a cell necrosis apparatus that provides deployableelectrodes that create a variety of different geometric cell necrosislesions.

SUMMARY OF THE INVENTION

Accordingly, an object of the invention is to provide a cell necrosisapparatus that provides tissue reduction at selected anatomical sites.

Another object of the invention is to provide a treatment apparatus tocreate cell necrosis.

Still another object of the invention is to provide a cell necrosisapparatus that has at least two electrodes which are deployable from anintroducer with curvature and a third electrode which is deployable withminimal curvature.

Yet another object of the invention is to provide a cell necrosisapparatus with selectively deployed electrodes.

A further object of the invention is to provide a cell necrosisapparatus that is configured to deploy electrodes selectively at atissue site to create a desired cell necrosis lesion.

These and other objects of the invention are achieved in a cell necrosisapparatus including an introducer with a distal end sufficiently sharpto penetrate tissue, an energy delivery including a plurality ofelectrodes and a slidable sensing member. Each electrode of theplurality of electrodes has a tissue piercing distal end and ispositionable in the introducer as the introducer is advanced throughtissue. At least one electrode of the plurality of electrodes isdeployable with curvature from the introducer. The slidable sensingmember is positionable within the introducer and electrically coupled tothe energy delivery device. The sensing member is configured to measurea property of the energy delivery device or at least one electrode ofthe plurality of electrodes.

In another embodiment, a cell necrosis apparatus has an energy deliverydevice that includes a first RF electrode with a tissue piercing distalportion and a second RF electrode with a tissue piercing distal portion.The first and second RF electrodes are positionable in the introducer asthe introducer is advanced through tissue and deployable with curvaturefrom the introducer at a selected tissue site. A groundpad electrode iscoupled to the first and second RF electrodes. A first sensor is coupledto the groundpad electrode.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is cross-sectional view of a cell necrosis apparatus of thepresent invention with two deployable electrodes and an deployablemember at a selected cell necrosis tissue site.

FIG. 2(a) illustrates a cross-sectional view of an embodiment of a cellnecrosis apparatus of the present invention with a first and a secondset of deployable electrodes.

FIG. 2(b) illustrates the cell necrosis apparatus of FIG. 2(a)positioned at a targeted cell necrosis tissue site.

FIG. 3 illustrates an embodiment of a cell necrosis apparatus of thepresent invention with multiple sensors coupled to electrodes.

FIG. 4 illustrates a spherical cross-section of an electrode utilizedwith a cell necrosis apparatus of the present invention.

FIG. 5 illustrates an elliptical cross-section of an electrode utilizedwith a cell necrosis apparatus of the present invention.

FIG. 6 illustrates a cross-section of an electrode utilized with a cellnecrosis apparatus of the present invention with a largercross-sectional length than its width.

FIG. 7 illustrates a cross-section of an electrode utilized with a cellnecrosis apparatus of the present invention with a flat-like externalsurface.

FIG. 8 is a perspective view of a cell necrosis apparatus of the presentinvention that includes insulation sleeves positioned at exteriorsurfaces of the electrodes.

FIG. 9 is a perspective view of a cell necrosis apparatus of the presentinvention that includes multiple insulation sleeves thatcircumferentially insulate selected sections of the electrodes.

FIG. 10 is a perspective view of a cell necrosis apparatus of thepresent invention with insulation that extends along longitudinalsections of the electrodes to define adjacent longitudinal energydelivery surfaces.

FIG. 11 is a cross-sectional view of the cell necrosis apparatus of FIG.10 taken along the lines 11—11.

FIG. 12 is a perspective view of a cell necrosis apparatus of thepresent invention with insulation that extends along longitudinalsections of the electrodes and does not continue to distal ends of theelectrodes.

FIG. 13 is a cross-sectional view illustrating the positioning ofelectrodes adjacent to a selected tissue site with insulation thatextends along a longitudinal surface of the electrodes and theinsulation faces away from a central axis of the selected tissue site.

FIG. 14 is a cross-sectional view illustrating the positioning ofelectrodes at a selected tissue site with insulation that extends alonga longitudinal surface of the electrodes and the insulation faces towarda central axis of the selected tissue site.

FIG. 15 is a close-up perspective view of a surface area of an electrodebody at a distal end of an electrode of a cell necrosis apparatus of thepresent invention.

FIG. 16 is a perspective view of a cell necrosis apparatus of thepresent invention with spacers associated with each deployed electrode.

FIG. 17 is a cross-sectional view of a cell necrosis apparatus of thepresent invention illustrating a spacer, an associated electrode andinsulation inside the spacer.

FIG. 18 is a cross-sectional view of an embodiment of a cell necrosisapparatus of the present invention that includes a slidable member thatengages a power source to a contact coupled to the electrodes.

FIG. 19 is a cross-sectional view of the apparatus of FIG. 18 with theslidable member pulled back and disengaging the power source from theelectrodes.

FIG. 20 is a block diagram illustrating the inclusion of a controller,electromagnetic energy source and other electronic components of thepresent invention.

FIG. 21 is a block diagram illustrating an analog amplifier, analogmultiplexer and microprocessor used with the present invention.

DETAILED DESCRIPTION

Referring to FIG. 1, one embodiment of a cell necrosis apparatus 10includes an introducer 12 with a distal end 14 sufficiently sharp topenetrate tissue. An energy delivery device, generally denoted as 16,includes a first RF electrode 18 and a second RF electrode 20.Electrodes 18 and 20 are positionable in introducer 12 as introducer 12advances through tissue. Electrodes 18 and 20 have tissue piercingdistal ends 22 and 24, respectively. Electrodes 18 and 20 are selectablydeployed with curvature from a distal end 14 or a side port formed in adistal portion 26 of introducer 12 to a selected tissue site 28. Tissuesite 28 can be any tissue mass and can be a tumor to be ablated.Electrodes 18 and 20 are selectably deployed to be controllablypositioned at a desired location relative to tissue site 28 thatincludes internal placement, external placement at a periphery of tissuesite 28 and at any desired location relative to tissue site 28. Theselectable deployment of electrodes 18 and 20 can be achieved with theamount of advancement of electrodes 18 and 20 from introducer 12,independent advancement of electrodes 18 and 20 from introducer 12, thelengths and/or sizes of energy delivery surfaces of electrodes 18 and20, the variation in materials used for electrodes 18 and 20 as well asvariation of geometric configuration of electrodes 18 and 20 in theirdeployed states.

Electrodes 18 and 20 are in compacted positions while they arepositioned in introducer 12. As electrodes 18 and 20 are advanced fromintroducer 12 they move to a deployed state from their compactedconfigurations. Any number of electrodes can be included in energydelivery device 16. The electrodes of energy delivery device 16 can bedeployed simultaneously, in pairs, in sets and one at a time. Anelectrode advancement member 30 is coupled to energy delivery device 16.Electrode advancement member 30 can be actuated by the physician bymovement of a proximal end 32 relative to a longitudinal axis ofintroducer 12.

Introducer 12 can be flexible. In one embodiment, introducer 12 issufficiently flexible to pierce tissue, and move in any desireddirection through tissue to tissue site 28. In another embodiment,introducer 12 is sufficiently flexible to reverse its direction oftravel and move in direction back upon itself. In one embodiment,introducer 12 is more flexible than electrodes 18 and 20.

When introducer 12 reaches tissue site 28, including but not limited toa solid lesion, energy delivery device 16 is deployed preferably fromdistal end 14 of introducer 12. Energy delivery device 16 can also bedeployed from side ports formed in the body of introducer 12. In thedeployed state energy delivery device 16 becomes expanded from itscompacted configuration in introducer 12 and is selectively positionedrelative to the tissue site. Electrodes 18 and 20 can be portionedwithin an interior of the tissue site, at the exterior of the tissuesite as well as combinations thereof. Electrodes 18, 20 as well asthird, fourth, fifth, etc. electrodes are advanceable different lengthsfrom distal end 14 of introducer 12. In one embodiment, the electrodesof deployed energy delivery device 16 are positioned equally distant acentral axis of tissue site 28. Volumetric cell necrosis can proceedfrom the interior, exterior of tissue site 28 as well as variouscombinations thereof with each deployed electrode of energy deliverydevice 16 in order to create a selectable and predictable cell necrosis.

Electrodes 18 and 20 can be made of a variety of conductive materials,both metallic and non-metallic. One suitable material is type 304stainless steel of hypodermic quality. In some applications, all or aportion of electrodes 18 and 20 can be made of a shaped memory metal,such as NiTi, commercially available from Raychem Corporation, MenloPark, Calif. A radiopaque marker 21 can be coated on electrodes 18 and20 for visualization purposes.

Electrodes 18 and 20 can have different lengths that are advanced fromdistal end 14 of introducer 12. The lengths can be determined by theactual physical length of electrodes 18 and 20, the length of an energydelivery surface of electrodes 18 and 20 and the length of electrodes 18and 20 that is not covered by an insulator. Suitable lengths include butare not limited to 17.5 cm, 25.0 cm. and 30.0 cm. The actual lengths ofelectrodes 18 and 20 depends on the location of tissue site 28 to beablated, its distance from the skin, its accessibility as well aswhether or not the physician chooses a laparoscopic, percutaneous orother procedure.

A deployable member 34 can be coupled to electrode advancement member30. Deployable member 34 can provide a variety of different functionsincluding but not limited to the placement of a sensor at a selectedtissue site to measure/monitor temperature and/or impedance.Additionally, all or a portion of deployable member 34 can be an RFelectrode operable in bi-polar or mono-polar modes. Deployable member 34can also be a groundpad electrode.

A sensor 36 can be coupled to deployable member 34 at a distal end 38,or at any physical location of deployable member 34. In this manner,temperature and/or impedance is measured or monitored at a distalportion of tissue site 28 or at any position in or external to tissuesite 28. Deployable member 34 is deployable from distal end 14 ofintroducer 12 with less curvature than electrodes 18 and 20. Deployablemember 34 can be deployable from distal end 14 without substantially anycurvature.

Sensor 36 permits accurate measurement of temperature at tissue site 28in order to determine, (i) the extent of cell necrosis, (ii) the amountof cell necrosis, (iii) whether or not further cell necrosis is neededand (iv) the boundary or periphery of the ablated mass. Further, sensor36 reduces non-targeted tissue from being destroyed or ablated.

Sensor 36 is of conventional design, including but not limited tothermistors, thermocouples, resistive wires, and the like. A suitablethermal sensor 36 includes a T type thermocouple with copperconstantene, J type, E type, K type, fiber optics, resistive wires,thermocouple IR detectors, and the like. It will be appreciated thatsensor 36 need not be a thermal sensor.

Sensor 36 measures temperature and/or impedance to permit monitoring anda desired level of cell necrosis to be achieved without destroying toomuch tissue. This reduces damage to tissue surrounding the targeted massto be ablated. By monitoring the temperature at various points withinand outside of the interior of tissue site 28, a determination of theselected tissue mass periphery can be made, as well as a determinationof when cell necrosis is complete. If at any time sensor 36 determinesthat a desired cell necrosis temperature is exceeded, then anappropriate feedback signal is received at an energy source 40 coupledto energy delivery device 16 which then regulates the amount ofelectromagnetic energy delivered to electrodes 18 and 20.

Energy source 40 can be an RF power supply, an ultrasound energy source,a microwave generator, a resistive heating source, a laser and the like.Microwave antenna, optical fibers, resistive heating elements andultrasound transducers can be substituted for electrodes 18 and 20. Whenenergy source 40 is an RF power supply, 5 to 200 watts, preferably 5 to100, and still more preferably 5 to 50 watts of electromagnetic energyis delivered from energy source 40 to the electrodes of energy deliverydevice 16 without impeding out the electrodes.

Electrodes 18 and 20 are electromagnetically coupled to energy source40. The coupling can be direct from energy source 40 to each electrode18 and 20 respectively, or indirect by using a collet, sleeve and thelike which couples one or more electrodes to energy source 40.

Referring now to FIG. 2(a), another embodiment of apparatus 10 is shown.Apparatus 10 includes a first set 42 of RF electrodes and a second set44 of RF electrodes. First and second sets 42 and 44 can include one,two, three, four, five, etc, number of RF electrodes. As illustrated inFIG. 2, first set 42 includes electrodes 46 and 48, and second set 44includes electrodes 50 and 52. It will be appreciated that first andsecond sets 42 and 44 can include more or less electrodes than areillustrated in FIG. 2. Electrodes 46, 48, 50 and 52 have tissue piercingdistal ends, are positionable in introducer 12 in compacted states, andadvanceable to deployed states from distal end 14 with curvature fromintroducer 12. First set 42 is deployable a greater distance from distalend 14 than second set 44.

First and second sets 42 and 44 are coupled to electrode advancementmember 30 and can be simultaneously or individually deployed from distalend 14. Optionally coupled to first set 42, second set 44 and/orelectrode advancement member 30 is deployable member 34. Again,deployable member 34 can be coupled to a sensor 36 and all or a portionof deployable member 34 may be an RF electrode.

FIG. 2(b) illustrates the use of multiple sensors 36. Sensors 36 can becoupled to all or some of electrodes 46, 48, 50 and/or 52 at differentpositions of the electrodes. In various embodiments, sensors arepositioned at distal ends of electrodes 46 through 52, at positions thatare adjacent to distal end 14 of introducer 12, and at sites that aresomewhere intermediate between the distal and proximal portions ofdeployed lengths of the electrodes. Deployable member 34 can includesensors at distal and proximal portions of its deployed length in tissuesite 28. The placement of sensors 36 at different locations provides ameasurement of temperature and/or impedance, and a determination of thelevel of cell necrosis, created at tissue site 28.

As shown in FIG. 3, electrodes 18, 20, 46, 48, 50 and 52, collectively“electrodes 18”, can each be coupled to one or more sensors 36. Sensors36 can be at exterior surfaces of electrodes 18 at their distal ends,intermediate sections as well as adjacent to distal end 14 of introducer12. Some or all of electrodes 18 and deployable member 34 may have ahollow lumen by which a variety of different fluidic medium can beintroduced from proximal to distal ends. Suitable fluidic media includebut are not limited to electrolytic solutions, chemotherapeutic agents,drugs, medicaments, gene therapy agents, contrast agents and the like.

Electrode 18, as well as deployable member 34, can have a variety ofdifferent geometric cross-sections. Electrodes 18 can be made ofconductive solid or hollow straight wires of various shapes such asround, flat, triangular, rectangular, hexagonal, elliptical and thelike. FIGS. 4 and 5 illustrate circular and elliptical cross-sections.In FIG. 6, the cross-section has a greater length “L” than a width of“W”. In FIG. 7, the cross-sectional is elongated. In variousembodiments, the cross-sectional has a greater length than a width inorder to enhance ultrasonic viewability.

Each, a portion of all electrodes 18, as well as deployable member 34,have an exterior surface that is wholly or partially insulated andprovide a non-insulated area which is an energy delivery surface. InFIG. 8, two electrodes 18 include insulation 54. In the embodiment ofFIG. 8, insulation 54 is a sleeve that can be fixed or adjustable. Theactive area of electrodes 18 is non-insulated and provides an energydelivery surface 56.

In the embodiment illustrated in FIG. 9, insulation 54 is formed at theexterior of electrodes 18 in circumferential patterns, leaving aplurality of energy delivery surfaces 56. Referring now to theembodiment of FIGS. 10 and 11, insulation 54 extends along alongitudinal exterior surface of electrodes 18. Insulation 54 can extendalong a selected distance along a longitudinal length of electrodes 18and around a selectable portion of a circumference of electrodes 18. Invarious embodiments, sections of electrodes 18 can have insulation 54along selected longitudinal lengths of electrodes 18 as well ascompletely surround one or more circumferential sections of electrodes18. Insulation 54 positioned at the exterior of electrodes 18 can bevaried to define any desired shape, size and geometric energy deliverysurface 56.

In FIG. 12, insulation 54 is disposed on only one section of a deployedlength of electrodes 18. Energy delivery surfaces 56 are at distalportions of electrodes 18 as well as on longitudinal surfaces adjacentto insulation 54. In FIG. 13, insulation 54 extends along a longitudinallength of electrodes 18 can face toward a central axis 58 of tissue site28 and energy delivery surface 56 faces towards in a direction towardthe central axis 58. In FIG. 14, insulation 54 extends along alongitudinal length of electrodes 18 and faces away from central axis 58with energy delivery surface 56 facing away from central axis 58. In theembodiments illustrated in FIGS. 12 and 13, three electrodes 18 arepositioned inside or outside of a periphery of tissue site 28. It willbe appreciated that any number of electrodes 18 can be deployed with andwithout insulation to created a selectable cell necrosis pattern.

Electrodes 18 are selectably deployable from introducer 12 withcurvature to create any desired geometric area of cell necrosis. Theselectable deployment is achieved by having electrodes 18 with, (i)different advancement lengths from introducer 12, (ii) differentdeployed geometric configurations, (iii) variations in cross-sectionalgeometries, (iv) selectable insulation provided at each and/or all ofthe deployed electrodes 18, or (v) the use of adjustable insulation.

Deployed electrodes 18 can create a variety of different geometric cellnecrosis zones including but not limited to spherical, semi-spherical,spheroid, triangular, semi-triangular, square, semi-square, rectangular,semi-rectangular, conical, semi-conical, quadrilateral,semi-quadrilateral, semi-quadrilateral, rhomboidal, semi-rhomboidal,trapezoidal, semi-trapezoidal, combinations of the preceding, geometrieswith non-planar sections or sides, free-form and the like.

In one embodiment, the ultrasonic visibility of electrodes 18 through isenhanced by creating a larger electrode distal end surface area 60.Surface area 60 is the amount of the electrode body that is at thedistal end of electrodes 18. Referring now to FIG. 15 the distal end ofelectrode 18 has at cut angle of at least 25°, and in another embodimentthe cut angle is at least 30°. This creates a larger surface area 60.The distal end of deployable member 34 can also have these cut angles.

Referring to FIGS. 16 and 17, each or selected electrodes 18 anddeployable member 34 can have an associated spacer 62. Spacers 62 areadvanceable from distal end 14 of introducer 12 and can be coupled toadvancement member 30. Spacers 62 create a physical spacing thatseparates the deployed electrodes 18 from each other. The spacingcreated by spacers 62 also forms an area in tissue site 28 where thereis reduced or very little cell necrosis. Positioned within spacers 62 isan insulation 64 that electrically and electromagnetically isolateselectrodes 18 from spacers 62.

As illustrates in FIGS. 18 and 19, apparatus 10 can include a slidablemember 66 that provides an electrical connection between energy deliverydevice 16 and energy source 40. Slidable member 66 can be advancementmember 30 or a handpiece. In one embodiment, slidable member 66 has oneor two electrical contact pads 68 which can be resistor strips. When theslidable member is moved in a distal direction relative to distal end 14of introducer 12 resistor strips 68 become engaged with a contact 70(FIG. 18). Contact 70 is coupled to energy delivery device 16. Whenresistor strips 68 are engaged with contact 70, power and energy isdelivered from the energy source to electrodes 18. Slidable member 66 isthen moved in a distal direction and resistor strips become un-engagedwith contact 70 and the delivery of power from energy source 40 isdisrupted (FIG. 19). The employment of slidable member 66 provides aconvenient energy delivery device 16 on and off mechanism at the hand ofthe physician.

Resistor strips 68 can be used as sensors to recognize a variablesetting of one or all of electrodes 18 of energy delivery device 16.Resistor strips 68 can be used to measure resistance at a setting sothat a change in the resistance value can be measured as slidable member66 is moved and a corresponding change in the energy delivery surfacecorresponding to the electrodes 18. The resistance value can becorrelated to determine an optimal power in delivering energy fromenergy source 40. Gap sensors, including but not limited to lasers andultrasound, can be used to determine the variable setting.

Referring now to FIG. 20, a feedback control system 72 is connected toenergy source 40, sensors 36 and energy delivery device 16. Feedbackcontrol system 72 receives temperature or impedance data from sensors 36and the amount of electromagnetic energy received by energy deliverydevice 16 is modified from an initial setting of cell necrosis energyoutput, cell necrosis time, temperature, and current density (the “FourParameters”). Feedback control system 72 can automatically change any ofthe Four Parameters. Feedback control system 72 can detect impedance ortemperature and change any of the Four Parameters. Feedback controlsystem 72 can include a multiplexer to multiplex different electrodes 18and a temperature detection circuit that provides a control signalrepresentative of temperature or impedance detected at one or moresensors 36. A microprocessor can be connected to the temperature controlcircuit.

The user of apparatus 10 can input an impedance value which correspondsto a setting position located at apparatus 10. Based on this value,along with measured impedance values, feedback control system 72determines an optimal power and time need in the delivery of RF energy.Temperature is also sensed for monitoring and feedback purposes.Temperature can be maintained to a certain level by having feedbackcontrol system 72 adjust the power output automatically to maintain thatlevel.

In another embodiment, feedback control system 72 determines an optimalpower and time for a baseline setting. Ablation volumes or lesions areformed at the baseline first. Larger lesions can be obtained byextending the time of ablation after a center core is formed at thebaseline. A completion of lesion creation can be checked by advancingenergy delivery device 16 from distal end 14 of introducer 12 to adesired lesion size and by monitoring the temperature at the peripheryof the lesion.

In another embodiment, feedback control system 72 is programmed so thedelivery of energy to energy delivery device 16 is paused at certainintervals at which time temperature is measured. By comparing measuredtemperatures to desired temperatures feedback control system 72 canterminate or continue the delivery of power to electrodes 18 for anappropriate length of time.

The following discussion pertains particularly to the use of an RFenergy source and RF electrodes but applies to other energy deliverydevices and energy sources including but not limited to microwave,ultrasound, resistive heating, coherent and incoherent light, and thelike.

Current delivered to electrodes 18 is measured by a current sensor 74.Voltage is measured by voltage sensor 76. Impedance and power are thencalculated at power and impedance calculation device 78. These valuescan then be displayed at user interface and display 80. Signalsrepresentative of power and impedance values are received by controller82.

A control signal is generated by controller 82 that is proportional tothe difference between an actual measured value, and a desired value.The control signal is used by power circuits 84 to adjust the poweroutput in an appropriate amount in order to maintain the desired powerdelivered at energy delivery device 16.

In a similar manner, temperatures detected at sensors 36 providefeedback for determining the extent of cell necrosis, and when acompleted cell necrosis has reached the physical location of sensors 36.The actual temperatures are measured at temperature measurement device86 and the temperatures are displayed at user interface and display 80.A control signal is generated by controller 82 that is proportional tothe difference between an actual measured temperature, and a desiredtemperature. The control signal is used by power circuits 84 to adjustthe power output in an appropriate amount in order to maintain thedesired temperature delivered at the respective sensor 36. A multiplexercan be included to measure current, voltage and temperature, at thenumerous sensors 36, and energy is delivered to energy delivery device16. A variable electrode setting 88 is coupled to controller 82.

Controller 82 can be a digital or analog controller, or a computer withsoftware. When controller 82 is a computer it can include a CPU coupledthrough a system bus. On this system can be a keyboard, a disk drive, orother non-volatile memory systems, a display, and other peripherals, asare known in the art. Also coupled to the bus are a program memory and adata memory.

User interface and display 80 includes operator controls and a display.Controller 82 can be coupled to imaging systems, including but notlimited to ultrasound, CT scanners, X-ray, MRI, mammographic X-ray andthe like. Further, direct visualization and tactile imaging can beutilized.

The output of current sensor 74 and voltage sensor 76 is used bycontroller 82 to maintain a selected power level at energy deliverydevice 16. The amount of RF energy delivered controls the amount ofpower. A profile of power delivered can be incorporated in controller82, and a preset amount of energy to be delivered can also be profiled.

Circuitry, software and feedback to controller 82 result in processcontrol, and the maintenance of the selected power, and are used tochange, (i) the selected power, including RF, microwave, laser and thelike, (ii) the duty cycle (on-off and wattage), (iii) bi-polar ormono-polar energy delivery and (iv) infusion medium delivery, includingflow rate and pressure. These process variables are controlled andvaried, while maintaining the desired delivery of power independent ofchanges in voltage or current, based on temperatures monitored atsensors 36.

Referring now to FIG. 21, current sensor 74 and voltage sensor 76 areconnected to the input of an analog amplifier 90. Analog amplifier 90can be a conventional differential amplifier circuit for use withsensors 36. The output of analog amplifier 90 is sequentially connectedby an analog multiplexer 46 to the input of A/D converter 92. The outputof analog amplifier 90 is a voltage which represents the respectivesensed temperatures. Digitized amplifier output voltages are supplied byA/D converter 92 to a microprocessor 96. Microprocessor 96 may be ModelNo. 68HCII available from Motorola. However, it will be appreciated thatany suitable microprocessor or general purpose digital or analogcomputer can be used to calculate impedance or temperature.

Microprocessor 96 sequentially receives and stores digitalrepresentations of impedance and temperature. Each digital valuereceived by microprocessor 96 corresponds to different temperatures andimpedances.

Calculated power and impedance values can be indicated on user interfaceand display 80. Alternatively, or in addition to the numericalindication of power or impedance, calculated impedance and power valuescan be compared by microprocessor 96 with power and impedance limits.When the values exceed predetermined power or impedance values, awarning can be given on user interface and display 80, and additionally,the delivery of RF energy can be reduced, modified or interrupted. Acontrol signal from microprocessor 96 can modify the power levelsupplied by energy source 40.

The foregoing description of a preferred embodiment of the invention hasbeen presented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. Obviously, many modifications and variations will be apparentto practitioners skilled in this art. It is intended that the scope ofthe invention be defined by the following claims and their equivalents.

What is claimed is:
 1. A cell necrosis apparatus for use with an energysource, comprising: an introducer with a proximal end and a distal end;an energy delivery device including a plurality of electrodes, eachelectrode having a tissue piercing distal end and being positionable inthe introducer as the introducer is advanced through tissue, at leastone of said electrodes being deployable with curvature from theintroducer; and an advancement and retraction member operatively coupledto the plurality of electrodes to advance and retract the electrodes,said member being adapted for operative coupling to said energy source,and having relatively movable electrode-coupling elements for making andbreaking electrical contact when the advancement and retraction memberis advanced or retracted, respectively, in an axial direction, therebyto make and break electrical contact between said electrodes and saidenergy source, respectively.
 2. The apparatus of claim 1, wherein theintroducer distal end is sufficiently sharp to penetrate tissue.
 3. Theapparatus of claim 1, wherein the energy source is selected from thegroup consisting of an electrical energy source, an RF energy source, amicrowave energy source and an optical source.
 4. The apparatus of claim1, wherein said advancement and retraction member includes a resistiveelement carried at the distal end of the advancement and retractionmember, said resistive element being adapted for operative coupling tosaid energy source; and a contact member coupled to the energy deliverydevice, wherein the contact member is configured to engage the resistiveelement and establish electrical contact between the resistive elementand the energy delivery device.
 5. The apparatus of claim 4, wherein theresistive element is a resistor strip.
 6. The apparatus of claim 5,wherein the resistor strip includes a first and a second resistor strip.7. The apparatus of claim 6, wherein a first strip resistance is lessthan a second strip resistance.
 8. The apparatus of claim 6, wherein thecontact member is configured to engage at least one of the first or thesecond resistor strips.
 9. The apparatus of claim 5, wherein theresistor strip is configured to measure an electrical resistanceresponsive to movement of at least one of the energy delivery device orat least one of the plurality of electrodes.
 10. The apparatus of claim9, wherein the electrical resistance measurement is utilized to optimizea delivery of power to at least one of the plurality of electrodes. 11.The apparatus of claim 1, wherein said advancement and retraction memberincludes a sensing member for measuring a property of the energydelivery device or at least one of the plurality of electrodes, whereinsaid sensing member is selected from the group consisting of a gapsensor, an ultrasonic transducer and an optical sensor.
 12. Theapparatus of claim 11, wherein the advancement and retraction member isconfigured to control the delivery of power to the energy deliverydevice from the power source.
 13. The apparatus of claim 12, wherein theadvancement and retraction member is configured to provide on and offcontrol of power to the energy delivery device.
 14. The apparatus ofclaim 11, wherein the sensing member is at least partially positionedwithin a handpiece and is coupled to the proximal end of the introducer.15. The apparatus of claim 11, wherein the sensing member is configuredto measure a deployed length of one of the energy delivery device or atleast one electrode of the first or second sets of electrodes ofelectrodes.
 16. The apparatus of claim 1, wherein the advancement andretraction member functions as an electrode advancement member.
 17. Theapparatus of claim 1, wherein the plurality of electrodes includes afirst and second set of electrodes, wherein deployed portions of theelectrodes of the first and second sets of electrodes being configuredto create substantially the same geometric ablation shape at a firstdeployed position and a second deployed position.
 18. A cell necrosisapparatus for use with an energy source, comprising: an introducer witha distal end positionable in tissue; an energy delivery device includinga plurality of electrodes, each electrode having a tissue piercingdistal end and positionable in the introducer as the introducer isadvanced through tissue, at least one of said electrodes beingdeployable with curvature from the introducer; and an advancement andretraction member operatively coupled to the plurality of electrodes toadvance and retract said electrodes, said advancement and retractionmember being adapted for operative coupling to said energy source andhaving relatively movable electrode-coupling elements for making andbreaking electrical contact when the advancement and retraction memberis advanced or retracted, respectively, in an axial direction, therebyto make and break electrical contact between said electrode and saidenergy source, respectively; and said advancement and retraction memberincluding a sensing member for measuring a property of the energydelivery device or at least one electrode of the plurality ofelectrodes.
 19. A tissue treatment method, comprising: positioning in apatient a cell necrosis apparatus including an introducer; an energydelivery device including a plurality of electrodes, each electrode ofthe plurality of electrode having a tissue piercing distal end andpositionable in the introducer as the introducer is advanced throughtissue, at least one electrode of the plurality of electrodes beingdeployable with curvature from the introducer, and an advancement andretraction member operatively coupled to the plurality of electrodes toadvance and retract the electrodes, said member being adapted foroperative coupling to said energy source, and having relatively movableelectrode-coupling elements for making and breaking electrical contactwhen the advancement and retraction member is advanced or retracted,respectively, in an axial direction thereby to make and break electricalcontact between said electrode and said energy source, respectively, andincluding a sensing member for measuring a property of the energydelivery device or at least one electrode of the plurality ofelectrodes; deploying at least one electrode of the plurality ofelectrodes to define an ablation volume that includes solid-tumortissue; utilizing the sensing member to determine a characteristic of atleast one electrode of the plurality of electrodes; advancing theadvancement and retraction member in an axial direction to electricallyconnect the energy delivery device and the energy source; and deliveringenergy from the energy delivery device to the solid-tumor tissue. 20.The method of claim 19, at least one electrode of the plurality ofelectrodes is an RF electrode.
 21. The method of claim 19, furthercomprising: manipulating a handpiece coupled to the proximal end of theintroducer to deploy, advance or position at least one of the pluralityof electrodes.
 22. The method of claim 19, further comprising:controlling a delivery of power to at least one electrode of theplurality of electrodes from an energy source coupled to the apparatusutilizing the advancement and retraction member.
 23. The method of claim19, further comprising: measuring an electrical resistance responsive tomovement of at least one of the energy delivery device or at least oneelectrode of the plurality of electrodes.
 24. The method of claim 23,further comprising: controlling a delivery of power to at least oneelectrode of the plurality of electrodes from an energy source coupledto the apparatus responsive to the electrical resistance.
 25. The methodof claim 23, further comprising: optimizing a delivery of power to atleast one electrode of the plurality of electrodes from an energy sourcecoupled to the apparatus responsive to the electrical resistance. 26.The method of claim 19, further comprising: sliding the advancement andretraction member in a proximal direction relative to the introducer toelectrically disconnect the energy delivery device and the energysource; and ceasing delivery of energy from the energy delivery deviceto the solid-tumor tissue.
 27. The method of claim 19, furthercomprising: measuring the deployed length of one of the energy deliverydevice or at least one electrode of the plurality of electrodes bymeasuring the advancement of the advancement and retraction member. 28.The method of claim 19, further comprising: measuring the advancement ofthe advancement and retraction member with the sensing member; andcalculating a deployed area of one of the energy delivery device or atleast one electrode of the plurality of electrodes utilizing saidmeasurement.
 29. The method of claim 19, further comprising: measuringthe advancement of the advancement and retraction member with thesensing member; and calculating an area of an energy delivery surface ofone of the energy delivery device or at least one electrode of theplurality of electrodes is calculated utilizing said measurement.